The raid instance is supposed to be 4 times the size of Obsidian Sanctum, roughly the size of Alterac Valley

All the bosses will have new models

Ground mounts will be allowed.

The first four bosses will be non-linear before you get to the final three that are in a linear fashion, with Ragnaros at the end.

Ragnaros will be the final boss. It will NOT be an heroic-only encounter like Sinestra but the heroic version will be completely different from the normal one and developers wanted to make sure it feels really unique and pretty hardcore.

There will be more bars/meters to make it easier to watch certain mechanics in contrast to a simple debuff stacking

You won't need fire resistance and bosses won't have any either.

There will be epic recipies drops for all the usual professions.

Tier 12 Armor Sets

All T12 sets will be fire themed (duh)

Not new but reminder: Warlock will be themed after those awesome looking fire spiders

One plate set will be themed after the new fire giants (Anthricyst maybe?), the shoulders will be like the fire giant's face.

Set bonus will be firelands themed too and may resemble certain boss abilities

Raid Misc.

There will be a new Baradin Hold boss - another loot pinata (his words!)

The interviewer also asked for a second raid dungeon, Cory ignored that part and only answered the Baradin Hold part - interpret yourself.

Legendary:

The proc of the weapon will be offensive and not suited for healers

Weapon will be forged in major cities (Stormwind and Orgrimmar respectively)

There will be a 'very long' event with a lot of voice acting and the Blue Dragonflight.

Your guild will get a reward if you complete the achievement for the Legendary staff. It will most likely be a pet, it will have an unique look (not necessarily fiery) and a "legendary" feel.

Both 10 & 25 are supposed to get the weapon roughly at the same pace

25M will have s small advantage of getting the profession related parts done quicker

Nothing more on what profession related parts of the legendary are but it will be only a minor part of the progression to the legendary, focus is on raiding.

Encounter Journal (i.e. boss guides):

Will be on PTR

Will not require unlocking by killing the boss or something

They start with entries for Cataclysm content only but plan to add WotLK, TBC and vanilla entries too - later

There will be no loot wishlist but they have plans for that. Loot will be listed for encounters and sorted by difficulty.

Quests:

There will be a new epic level 85 questline around Thrall

It's not revealed if that is about Thrall (maybe) becoming the new aspect of earth

No epics as reward, story is the reward

This new questline can be completed entirely in solo.

New Daily quests will be "modular" i.e. you start with a base set of quests and earn a currency as reward. With this currency you can unlock other quest hubs and decide how you unlock all of the dailies. This will be acompanied by heavy phasing.

Phasing will only change the area, you will still be able to play with your friends even if they have progressed further

Thrall, the Aspect of Earth? Ugh. Really hope that was just Metzen fantasizing about his pet character. Do we really need the exact same plot twist two expansions in a row? And why, exactly, do we even need a new Aspect of Earth? They weren't in any hurry to replace Malygos when we killed him.

The news about Firelands sounds interesting, but I'll withhold judgement until I see the actual instance. Seven bosses seems rather low given how long it's taking them to get the instance out.

This time around they have, however, resulting in some sexy Ragnaros-styled armor, a new non-legendary version of his mace, Sulfuros, and a druid staff that drops off one of raid's other bosses that transforms the wielder into a molten cat.

The new dungeon even boasts three new mounts; one for competing all of the raid achievements, one random drop, and a special mount that drops every time Ragnaros fails.

All T12 sets will be fire themed (duh)
Not new but reminder: Warlock will be themed after those awesome looking fire spiders
One plate set will be themed after the new fire giants (Anthricyst maybe?), the shoulders will be like the fire giant's face.
Set bonus will be firelands themed too and may resemble certain boss abilities

I hope the warrior gets a set that looks like steel plating again. i just dont like this "stoned" gem look the t11 has.
something like t5 shoulders with a bit more of firelands style and a head like the t6 would be nice ^^

and the firelands themed set bonuses... sounds nice
and where was the information about warlock t12?

my apologies for my english.. im from germany, but i refuse to read buffed XD

This time around they have, however, resulting in some sexy Ragnaros-styled armor, a new non-legendary version of his mace, Sulfuros, and a druid staff that drops off one of raid's other bosses that transforms the wielder into a molten cat.

The new dungeon even boasts three new mounts; one for competing all of the raid achievements, one random drop, and a special mount that drops every time Ragnaros fails.

The size thing is weird to say the least I mean... 4*OS=AV? Really? I haven't been to either in months but that's not really how I remmember them. OS is a incredibly small room with couple dragons and AV is like... The biggest instanced zone ingame? Well maybe not the biggest but one of them.

Thrall, the Aspect of Earth? Ugh. Really hope that was just Metzen fantasizing about his pet character. Do we really need the exact same plot twist two expansions in a row? And why, exactly, do we even need a new Aspect of Earth? They weren't in any hurry to replace Malygos when we killed him.

The size thing is weird to say the least I mean... 4*OS=AV? Really? I haven't been to either in months but that's not really how I remmember them. OS is a incredibly small room with couple dragons and AV is like... The biggest instanced zone ingame? Well maybe not the biggest but one of them.

OS is actually pretty big. Just because it's only one boss doesn't mean it's tiny. If you put 4 of those together you get a pretty huge zone. Of course it won't LOOK like 4 OS - space will be used in totally different ways.

Kalecgos replaced him as the Leader of the Blue Dragonflight, he is no where near as powerful as Malygos was, due to him not being blessed by Norgannon, same thing here, except it's more stupid cause only dragons should be able to become Aspects, seems like a really bad retcon if it's true.